I'm sure that this has been asked here a hundred times, but I couldn't find the thread. Why is is that some BA overseas flights use Terminal 1 (NRT,HKG,LAX, SFO, JNB etc), when all the others use Term 4? And further to that, why do El Al & SAA use it too? (I seem to rememeber for that for years El Al & SAA have, correct?)

I can appreciate that AMS uses T4 given the connection traffic, but why T1 for "select" cities?

While I'm on the topic, who will use T5 once it's open?

Thanks in advance.